1. Field of the Invention
The present invention relates to a position-detecting and steering control system for use in a moving vehicle, and more particularly to a position-detecting and steering control system for use in a moving vehicle such as a moving automobile, an unmanned mobile and carrying device in a factory, or an automated vehicle for use in agriculture, civil engineering machinery and the like.
2. Description of the Prior Art
Heretofore, as a system for detecting a current position of a moving body such as the moving vehicles as described above, there has been proposed a system provided with a means for scanning a light beam emitted from a moving body in the circumferential direction or every azimuthal directions centering around the moving body, light-reflecting means for reflecting to return the light beam in the direction of incident light and secured at at least three positions apart from the moving body, and a beam receiver means for receiving light reflected from the light-reflecting means (Japanese Patent Laid-open No. 67476/1984).
In the above mentioned prior art, differential azimuths between adjoining two of three light-reflecting means centering around the moving body are detected on the basis of received beam output of the light-receiving means, and then a position of the moving body is operated based on the detected differential azimuths and positional information of the light-reflecting means which have been previously set.
In the above described system, however, problems have occurred where the light beam emitted from a beam source mounted on the moving vehicle could not be directed to the light-reflecting means positioned at reference points because of an inclination or vibration of the moving vehicle, or where the light-receiving means on the moving vehicle receives light reflected from objects other than the expected light-reflecting means described above.
When real reflected light is not positively received by a light-receiving means, the position of the moving vehicle is erroneously calculated so that the moving vehicle cannot be traveled along a prescribed course.
Meanwhile, there has been proposed a method for detecting positions of the moving body which is so arranged that the scanning rate and scanning angle of the light beam are allowed to change thereby positively directing the light beam to the light-reflecting means by, for example, Japanese Patent Laid-open No. 104503/1984. Furthermore, Japanese Patent Laid-open No. 211816/1984 proposes a system for detecting positions of the moving body which is so arranged that incident light produced on the moving body is converted into intermittent and periodical light, whereby the incident light is allowed to discriminate from the light emitted from the other light source.
However, these prior systems involve problems that both the system constructions become complicated, for example, the former method which changes a scanning rate and angle of light beam is required to vary frequently driving current in an optical scanner, and the latter system which is adapted to produce intermittent and periodical incident light is required to provide a complicated beam source section for producing the incident light.
In either prior art system, there has been a further problem that the position of the moving vehicle cannot be detected where there is any trouble in a photosensor system such as a light-receiving means and light-reflecting means, or where there is a trouble in a rotary table driving section for revolving the photosensor system such as the light-receiving means and the like, or where some or all of the light-reflecting means from which the reference signals of calculation are obtained tilt over.
Furthermore, there has been a problem that the reflected light cannot be positively received by a moving vehicle because of contamination on a reflecting surface of light-reflecting means, or such unexpected appearance of obstruction that man or other substance goes across the light-reflecting means as well as obstacles due to inclination or vibration of the moving vehicle. In this respect, these problems as mentioned above could not have been solved by only the above described prior art systems.